Guaiacol glycerine ether for a long time has been used as a means for medicinal lobotomy, see Rompp; Chemie-Lexikon, 5th edition, Volume II.
It is produced, e.g. by reaction of guaiacol with epichlorohydrin in the presence of molar amounts of sodium hydroxide in water (Yakugaku Zasshi 87(8), 967 (1967)). This reaction, however, requires relatively long reaction times at a temperature of around 85.degree.-90.degree. C. and only results in small yields (32%) of guaiacol glycerine ether.
Furthermore, there is described the reaction with glycerine-.alpha.-monochlorohydrin. Thereby it is likewise possible to start from epichlorohydrin and to hydrolyze this in a precusor reaction to glycerine-.alpha.-monochlorohydrin by addition of a suitable aqueous acid (e.g. 0.2% H.sub.2 SO.sub.4) (Polish patent No. 48485 (1964)). It is also necessary in the reaction with glycerine-.alpha.-monochlorohydrin to use molar amounts of an alkaline catalyst such as sodium hydroxide. The reaction is principally carried out in water, i.e. aqueous alkali or aqueous methanol (Spanish patent No. 212920 (1954), Czech patent No. 107107 (1963), Polish patent No. 42379 (1959)). Of course there has also been described the addition of toluene/butanol mixtures (German OS No. 2256506 (1973)).
All of these processes, if they are carried out at room temperature, proceed only very slowly while on the other hand, at the temperature of the boiling point of the solvent there must be dealt with the considerable formation of color. Furthermore, per 100 kg of guaiacol there is formed about 30 kg of sodium chloride which must be separated from the reaction solution by suitable procedures, to avoid loss of yield it must be washed, and disposed of. Furthermore the process is characterized by a considerable energy cost since solvents having high vaporization enthalpies are distilled.
Besides it is also known to employ 2,3-epoxypropanol, i.e. glycidol, for the reaction with phenols, among others, p-methoxyphenol, see British Pat. No. 628497; tertiary amine or quaternary ammonium salts function as catalysts.
This reaction with glycidol in place of glycerine-.alpha.-monochlorohydrin has the great advantage that it can be operated free from solvent and no sodium chloride is obtained. Through this there is eliminated the separation of the sodium chloride and besides the product is free from chlorine.
The disadvantage of this reaction according to the data of the mentioned British Patent is first of all in the yield, which is not very high; employing the mentioned p-methoxyphenol, it is only 50-65% as crude product.
Besides, in applying this reaction to o-methoxyphenol, i.e. guaiacol, the product obtained only has a very low purity. It still contains a considerable portion of the unreacted guaiacol as well as polymeric impurities, besides residue of the catalyst. Also the product is colored.
The purity of the product can be improved by repeated distillation but in addition to the industrial expense the yield naturally goes down still more by such procedure.
The goal of the invention was to develop a process for the production of guaiacol glycerine ether in which the product is obtained in good yield and purity.